JPS599896A - Radio wave sealing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radio wave seal for a consumer high frequency heating device, commonly called a microwave oven.

Microwave ovens are widely used to heat and cook objects using high-frequency sound energy, but radio waves leak to the outside through a gap between the heating chamber and the door (hereinafter referred to as a radio wave passage).

In recent years, society's awareness of the effects of radio wave leakage on the human body has increased, and in order to suppress the amount of radio wave leakage below an acceptable range, radio wave passages are equipped with a radio wave leakage prevention mechanism (hereinafter referred to as a radio wave seal). .

A generally well-known radio wave sticker is a chalk sticker.

A choke seal prevents the entrance of the radio wave path from being short-circuited by making both the dimension from the entrance of the radio wave path to the radio wave resonant groove and the length of the radio wave resonant groove equal to one-fourth of the wavelength of the high frequency generation source used. It is equivalent to the radio wave seal function and performs the ideal radio wave seal function.

Also, recent microwave ovens use stirrer fans to improve heating efficiency. Since the radio wave is disturbed, a choke seal alone cannot perform the radio wave sealing function in the complicated direction of radio wave propagation. Therefore, there are also radio wave seals that are equipped with slots with a periodic structure in the radio wave passage and the electromagnetic resonance charge to restrict the direction of radio wave propagation.

Furthermore, it is well known that a dielectric material is loaded in the @ wave resonance groove to reduce the length of the radio wave resonance groove and make it more compact (9).

As mentioned above, it is necessary for conventional choke seals that the dimensions from the entrance of the radio wave passage to the radio wave resonance groove and the dimensions of the radio wave resonance groove are both 1/4 wavelength, and there is a natural limit to the compactness of radio wave seals. Gaa f? -0 Also, if a slit is made in the radio wave path, the gap between the radio wave path will be covered with a low dielectric cover to cover the radio wave sole part, which contains a low dielectric material, from the viewpoint of aesthetics, etc. The body cover is necessarily thicker, which makes it easier for radio waves to pass through. On the other hand, even in the design of radio wave seals, there is a drawback that the development period is time-consuming due to qualitative experiments.

The present invention partially short-circuits the configuration of the radio wave path with a T-branch,
A parallel plate line is used from the entrance of the radio wave path to the T-branch opening, and the T-branch part has a configuration in which parallel transmission lines are arranged for the entire period, or a parallel plate line metal plate is used on the heating chamber side of the opposing parallel transmission lines in the T-branch part. By using a microstrip line in which the entire cyclostrip line is formed, and a microstrip line in which parallel transmission lines are arranged throughout the entire cycle from the T-branch opening to the end of the radio wave path, the radio wave sealing mechanism can be made more compact and the radio wave sealing performance can be improved. The object of the present invention is to provide a radio wave sealing device for a high frequency heating device.

Hereinafter, before explaining the present invention using drawings, the characteristics of the present invention will be described.
- By short-circuiting at an appropriate position, power is not transmitted between the other two ports.''As mentioned above, by periodically arranging parallel transmission lines in a part of the radio wave path, complicated radio wave propagation can be achieved. It exhibits sufficient radio wave sealing performance in all directions.

In addition, in making the radio wave seal more compact, the length from the entrance of the radio wave passage to the radio wave resonant groove and the length of the radio wave resonant groove are both reduced to 1/4 of the conventional Nayo Seal.
T
We introduced a method of analyzing a radio wave path system with a constant amount of energy by replacing all radio wave paths with branches with impedances and reducing the amount of radio wave leakage itself.

This constant energy analysis method assumes an impedance ZL at the end of a radio wave path in which parallel transmission lines are periodically arranged. Introducing this ZL impedance is
If sleep leaks to the outside space through the radio wave path, ZL
The idea is that energy is consumed with an impedance of Since the radio wave path has a certain finite gap, the impedance ZL always has a certain finite value. Conventionally, this Zt, the impedance is ZL
= Q, and could only think qualitatively by simply reducing the impedance at the entrance to the radio wave path.

By the way, is the amount of radio wave leakage based on this constant energy analysis method? In order to reduce this, it is equivalent to reducing the energy consumed by ZL. Therefore, the energy consumed by the ZL is reduced by using the characteristic sound of the T-branch circuit as described above.

Furthermore, according to this constant energy analysis method, it was discovered that the amount of radio wave leakage from the entrance of the radio wave passage to the T-branch opening can be reduced by using a wavelength smaller than the conventional one-quarter wavelength. This enables a compact radio wave sealing device with excellent performance.

Furthermore, in this constant energy analysis method, the radio wave path is considered to be a parallel transmission line, but it is possible to configure a parallel plate line from the entrance of the radio wave path to the T-branch opening, or to use the heating chamber side of the opposing parallel transmission lines at the T-branch. It was experimentally confirmed that the amount of radio wave leakage does not change even in a configuration in which a microstrip line is formed by using flat parallel transmission lines. This means that from the entrance of the radio wave path to the T-branch opening,
Since it is composed of parallel flat plates, there is no need for a cover such as a low dielectric material, and there is no need to consider the thickness of the cover for the gap between the heating chamber and the door.
It is possible to narrow down the number by k.

This will be explained using the drawings.

FIG. 1 shows a choke seal of a conventional microwave oven. Does the radio wave propagate to the outside from the entrance 6 of the radio wave passage 6 formed by the heating chamber main body wall 2 and door 3?In the case of a choke seal, the radio wave resonant grooved lower! An ideal electromagnetic seal is constructed by setting the dimensions of both the length and the radio wave resonance groove 8 to 1/4 length, and furthermore, 9
By arranging the slits in a periodic manner like this, it has excellent radio wave sealing characteristics even for complicated radio wave propagation.

FIG. 2 shows a radio wave sole portion showing an embodiment of the present invention. In FIG. 2, the dielectric material is omitted. From the radio wave passage entrance 6' to the T-branch entrance 10-1, based on the constant energy analysis method, the length is 10 mm, which is shorter than one-quarter of the shingle length, and it is constructed of parallel flat plates.

The T-branch portion and the T-branch portion have parallel transmission lines 11 arranged periodically, and extend from the T-branch opening 10 to the vicinity 4 of the terminal end of the radio wave path 5'.
In order to prevent variations in the transmission line ', some 3 mm transmission lines are fully connected.

FIG. 3 is a sectional view of the radio wave sole portion when a dielectric material is loaded. Dielectric 1 from T-branch opening 10 to T-branch termination 12 trenches and from T-branch opening 10 to radio wave path termination 4'
4 is loaded.

In the above configuration, the radio waves that are about to leak to the outside through the radio wave path 5' propagate between 6' and 4' because the T-branch section 1-0-12 has a dimension close to a quarter wavelength. Furthermore, it is difficult to connect the T-branch opening 10 from the radio channel entrance 6'.
In terms of size, it has a parallel plate structure, and the heating chamber wall surface 2' and the door wall surface 3' form a close contact state, so that the entire amount of radio waves that are to be transmitted can be absorbed.

The distance from the radio wave passage entrance 6' to the T-branch opening 10 is 4
It was confirmed that the radio wave sealing performance was better when the length was smaller than 1/11 JI length, and by loading a dielectric material on the T-branch, a compact radio wave seal was made possible. Furthermore, even for complex radio wave propagation, since the parallel transmission lines are arranged periodically, the propagation in the arrangement direction is restricted.

Note that this is not limited to one embodiment of the present invention, but as another embodiment, as shown in FIG. 4, an all-plane line configuration on the heating chamber side of a parallel transmission line where the T-branch portions are homologous may be used. It has been experimentally confirmed that the radio wave seal performance remains unchanged.

As described above, the present invention provides a part of the T-branch part in the radio wave passage, periodically arranges the T-branch part and the T-branch opening to the radio wave passage entrance dimension with parallel transmission lines, and completely connects the radio wave passage entrance to the T-branch opening 1. By adopting a parallel plate line configuration, a compact radio wave seal is possible, and the following effects can be obtained.

(1) Rather than designing a mechanism for an experimental radio wave seal as in the past, the dragonfly mechanism can be designed theoretically, which shortens the design period.

(2) A compact radio wave seal is possible.

(3) Since the parallel transmission lines near the end of the radio wave path are continuous, variations in the transmission lines are eliminated.

(- Easier to manufacture than configuring all radio wave paths as parallel transmission lines.

(5) External enemies can also create smart doors, reduce the amount of materials, and make them lighter.

(6) Dielectric cover can reduce -g1s.

('7) Since the mechanical strength of the transmission line near the end of the radio wave path and the dimensional accuracy of manufacturing can be maintained, the radio wave sealing characteristics are stabilized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing a conventional choke seal with a slit If, FIG. 2 is a cross-sectional perspective view showing an embodiment of the present invention, FIG. 3 is a cross-sectional view of a radio wave seal mechanism loaded with a dielectric, and FIG. The figure is a cross-sectional perspective view of another embodiment of the present invention. 1.1'...Heating chamber, 3. 3'・・・・・・
Door, 5.5′ mountain...Radio wave passage, 10...T
Branch opening, 12...T branch end, 414'...
... Radio wave path termination, 11 ... Parallel transmission line, 13 ... Parallel plate line, 14 ... Dielectric material.

Claims (2)

[Claims] (1) It has a heating chamber in which the object to be heated is placed and a door that can be opened and closed to take the object in and out, and the radio wave path formed by the heating chamber and the door is composed of seven branch paths with short-circuited ends. From the opening of the seven branch paths to the end of the short-circuit surface and from the T-branch opening to the end of the radio wave path, a periodic transmission line configuration is taken in the direction around the door, and from the entrance of the radio wave path to the end of the radio wave path.
The radio wave seal device has a parallel plate line configuration up to the branch opening, and its dimensions are smaller than a quarter wavelength. (2) The radio wave sealing device according to claim 1, wherein a dielectric material is loaded in the radio wave path constituting the T-branch.